The antibiotic bacilysin, produced by a number of strains of Bacilus subtilis, was first encountered by Abraham and his co-workers in 1946. Preliminary work on the production and purification of bacilysin was carried out by Abraham and Guy Newton, but the work ended in 1948 due to insufficient resources and the Dunn School's increasing interest in cephalosporins. Abraham and his colleagues returned to research on this antibiotic in the early 1960s.